Rapid development of a semiconductor industry in recent years has created a continued demand for progressively greater numbers of contacts and leads in a specific amount of space. An individual chip may require a substantial number of contacts, all within the area of the chip surface. For instance, a complex semiconductor chip in current practice may have rows of contacts along the edges. The contacts in each such row are spaced apart from one another at center-to-center distances of 0.1 mm or less and, in some cases, 0.07 mm or less. These distances are expected to decrease progressively with continued development in the field of semiconductor fabrication.
Each contact on the chip must be connected to external circuitry, such as the circuitry of a supporting substrate or circuit panel. Prefabricated arrays of leads or discrete wires are typically employed for making such interconnections. With such closely-spaced contacts, the leads connected to the chip contacts, must be extremely fine structures, typically less than 0.035 mm wide. Such fine structures are susceptible to damage and deformation. With closely spaced contacts, even minor deviation of a lead from its normal position will result in misalignment of the leads and contacts. Thus, a given lead may be out of alignment with the proper contact on the chip or substrate, or else it may be erroneously aligned with an adjacent contact. Either condition will yield a defective chip assembly. Errors of this nature materially reduce the yield of good devices and introduce defects into the product stream. These problems are particularly acute with those chips having relatively fine contact spacings and small distances between adjacent contacts.
Various approaches have been taken towards development of technological processes, tools and the like designed to a accommodate high concentration of contacts and leads as well as extremely fine nature of the components involved in these manufacturing operations. For example, commonly assigned U.S. patent application Ser. No. 919,772 filed Jul. 24, 1992 (the disclosure of which is hereby incorporated by reference) provides a semiconductor connection component and method which quite successfully deal with the above-mentioned problems by providing a connection component having a gap with, in some cases, one or more leads having elongated connection sections extending across such gap. The connection component is disposed on the chip or other part to be connected so that the connection sections of the leads extend above the contacts of the chip. During the bonding operation such connection sections are displaced relative to the connection component and engaged with the contacts. In certain preferred embodiments of these novel methods, prior to the bonding operation, the connection sections are situated substantially parallel to each other in a row and aligned with the corresponding contacts of the semiconductor chip. This system allows a bonding tool to engage and bond each connection section in sequence. However, as the center-to-center distance between contacts on the chip, and hence the center-to-center distance between adjacent lead connection sections decrease, this system encounters a limit. At extremely small center to center distances, it does not provide enough space to accommodate a shank of the tool during the bonding operation. As the tool moves a connection section downwardly to engage it with the corresponding contact, the shank of the tool may interfere with the next adjacent unbonded connection section in the row. As further explained below, such interference can be caused or aggravated by attempts to compensate for lead misalignment and by the shape of the tool shank. Thus, there has been a considerable need for a process and a connection component which alleviate these concerns and which permit use of the as above process at even smaller contact center-to-center distances.
Typically, the lead includes a connection section having a first end fixed to the body of the connection component and having a second end detachably connected to the body by a frangible section of the lead. The frangible section breaks during downward movement of the tool. As further described in copending, commonly assigned U.S. patent application Ser. No. 096,693 (the disclosure of which is hereby incorporated by reference herein), the tool used in bonding the connection sections of the leads desirably moves in the longitudinal direction of the lead connection section. The longitudinal movement is normally away from the frangible section of the lead and toward the fixed or first end, i.e., toward the end which remains attached to the connection component body. This movement tends to bend the lead, typically into an S-shaped configuration prior to bonding. It effectively relieves stress in the lead induced by the downward movement of the tool.
During this longitudinal movement, the bond region of the lead engaged with the tool should move along with the tool along with the tool. If tool allowing the tool to move lengthwise along the lead, the S-shaped configuration may not be achieved. Thus, further improvement in this aspect of the bonding operation is also desirable.